Fibronectin is a well characterized, extracellular, structural glycoprotein which interacts with other extracellular matrix molecules and promotes cell attachment and spreading (Ruoslahti, et al., 1981; Hynes and Yamada, 1982; Furcht, 1983). The ability of cells to bind to fibronectin can now be accounted for by the tripeptide L-arginyl-glycyl-L-aspartic acid (Arg-Gly-Asp), a sequence which is found in the cell attachment domain of fibronectin (Pierschbacher, et al., 1983; Pierschbacher and Ruoslahti, 1984a; 1984b). Small synthetic peptides containing this sequence promote cell attachment when used to coat a surface and inhibit the attachment of cells to fibronectin-coated substrata when presented in a soluble form (Pierschbacher and Ruoslahti, 1984a; 1984b).
Fibronectin is not the only adhesion-promoting molecule in the immediate environs of cells (Kleinman, et al., 1981). Collagens (Rubin, et al., 1981), laminin (Terranova, et al., 1980; Carlsson, et al., 1981), vitronectin (Hayman, et al., 1983; Barnes and Silnutzer, 1983), and molecules such as those identified by polyclonal (Damsky, et al., 1983) and monoclonal (Oesch and Birchmeier, 1982) antibodies may also contribute to adhesion.